1. Field
The present invention relates to an adhesive film and a display member using the same.
2. Description of the Related Art
A pressure-sensitive adhesive for an optical member generally used for a liquid crystal display (LCD) is prepared from a composition including a binder, a crosslinker, a coupling agent, a solvent and additives, and is subjected to an aging process in which the adhesive is left under certain temperature and humidity conditions after a drying process for volatizing the solvent. In general, the aging process may be performed quickly under high-temperature and high-humidity conditions, for example, at about 35° C. and about 45% RH, and requires a long period of time, for example, several days, under low-temperature or low-humidity conditions. Thus, the aging process requires an aging chamber for creating certain temperature and humidity conditions or a long period of time and thus is disadvantageous in terms of cost and productivity.
A general pressure-sensitive adhesive includes an acrylic monomer, which includes an acidic component containing a carboxyl group.
In a touchscreen LCD panel using indium tin oxide (ITO), ITO is oxidized by an acid component of a pressure-sensitive adhesive and increases resistance, thereby deteriorating touchscreen characteristics.
Further, an optical film using a pressure-sensitive adhesive contracts or expands in severe environments of high temperature (for example, 85° C.) and high humidity, and peels from the LCD panel to cause defects, such as detachment or generation of bubbles, when the pressure-sensitive adhesive has insufficient durability. In addition, light leakage may occur due to a difference in dimensional change between the optical film and a pressure-sensitive adhesive layer. Thus, the pressure-sensitive adhesive is required to have high durability and physical properties for controlling or relieving stress by contraction or expansion of the optical film to suppress light leakage. In addition, the pressure-sensitive adhesive is required to have excellent re-peelability for reworking operation to remove foreign matter or processing defect when an optical film including a pressure-sensitive adhesive layer is attached to a panel.
Korean Patent Publication No. 2010-0003689 A discloses a pressure-sensitive adhesive composition which has a weight average molecular weight of 800,000 g/mol to 2,000,000 g/mol and includes an aromatic group-containing acrylic copolymer and an optically anisotropic compound having a melting point of room temperature or less to achieve low light leakage.